The following studies of the newest of the pancreatic hormones, pancreatic polypeptide, are in progress. 1. Large scale isolation of avian and canine pancreatic polypeptide (PP). 2. A by product of these preparations is pro avian PP and pro canine PP. These hormone precursors are being purified at this time. 3. Determination of the conformation of avain PP in solution by circular dichroism, sedimentation dimerization iodination studies. 4. Isolation of PP from primitive species. 5. Study of PP binding by organs and membranes. 6. A study of PP secretion in pancreas pieces.